How about adding ESMTP support with SSL support to Trashmail? At least it would prevent most of traditional internet eavesdropping.

I will try to implement this, but first I will do the whitelisting function that I need urgently to use also for myself!!

Its now implemented. The only bad thing is that the certificate is not recognized by any known CA.
But simple eavesdropping is only possible with man-in-the middle attack with 2 possibilities (protocol hacking and private/public key exchange proxying).